This invention relates to apparatus for mixing and dispensing a liquid with another material, such as a solid or another liquid.
Various devices have been proposed for mixing a liquid with a solid or another liquid to form a fresh mixture just before use. Such devices are particularly useful in preparing aqueous solutions of medicaments which are not very stable in solution, and therefore should be administered shortly after mixing.
U.S. Pat. No.3,542,023 to Ogle (1970 ) discloses a successful two-compartment device for mixing a medicament in a container compartment with a liquid in a syringe compartment just before administration. U.S. Pat. No.4,516,967 to Kopfer (1985 ) discloses another two-compartment device for mixing a medicament powder with a liquid just prior to use.
One disadvantage of some of the prior art devices is that they use a cannula permanently secured at one end to a syringe compartment of the device so the cannula is used both for the mixing operation and subsequent administration of the mixture. Accordingly, the diameter of the cannula must be relatively small to permit its use on a patient or at an injection site. The restricted size of the cannula makes it difficult and time-consuming to achieve proper mixing of the liquid and the medicament. Another disadvantage of some of the prior art devices is that after the mixing is completed, the cannula is withdrawn from the container for the medicament, and the sharp end of the cannula is exposed. This creates a hazard to operating personnel, especially when handling drugs which are toxic, mutagenic, or otherwise dangerous if allowed to contact a human being in an uncontrolled or improper manner. The anti-tumor drugs are an example of a class of medicaments presenting this hazard.
Another disadvantage of the prior art devices is they are bulky, expensive to make, and do not provide for safe disposal of used medicament containers, or the cannulas used for mixing.